Published online Dec 16, 2018. doi: 10.4253/wjge.v10.i12.400
Peer-review started: July 27, 2018
First decision: August 20, 2018
Revised: August 31, 2018
Accepted: November 15, 2018
Article in press: November 15, 2018
Published online: December 16, 2018
Obscure gastrointestinal bleeding (OGIB) is a challenge to the professional who faces this occurrence. Although only a small part of these bleeds occurs in the midgut, the difficulty in accessing it implies a longer interval between the onset of symptoms and diagnosis and therapy. Initially, we used enteroscopes with single balloon, including spiral and double balloon overtubes, which is the most commonly used. Subsequently, the endoscopic capsule was introduced, allowing a greater index of complete observation of the small intestine with greater comfort to the patient. A weakness includes the therapeutic impossibility present in balloon enteroscopy. Due to the particularities of each of the methods, we should seek data in the available scientific literature to support our most appropriate diagnostic decision.
Video capsule endoscopy (VCE) and double-balloon enteroscopy (DBE) are recognized endoscopic diagnostic approaches for OGIB, for which vascular origins represent the most common source. Our initial motivation was to determine whether there is a preferential diagnostic approach in OGIB by vascular origin that maintains high accuracy. From the literature review about the subject, we realized some characteristics that we interpreted as important limitations in the previous works. Thereafter, this study sought to remove these limitations and to follow a rigorous methodological approach in the selection and analysis to enhance knowledge about accuracy data.
We want to compare accuracy data between the two most widespread indicated endoscopic approach methods in OGIB: VCE and DBE. It was possible to obtain a large sample of patients submitted to both methods from the literature. We believe that future systematic reviews on this issue can be based on our selection and analysis methodology. In addition, new studies that will be published can be added to update and provide a greater dimension to the theme.
This systematic review was conducted according to the PRISMA Statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and registered on PROSPERO international database. The search was performed in the electronic databases MedLine (via PubMed), LILACS (via BVS) and Cochrane/CENTRAL virtual databases. The QUADAS-2 tool was used to evaluate the risk of bias and the applicability of primary diagnostic accuracy studies and the incorporation of recent studies on the OGIB approach. All articles were read and chosen based on common consensus among three authors, and restricted inclusion criteria provide greater magnitude and accuracy.
Seventeen studies were included with 3150 exams performed in 2043 patients, resulting in the identification of 1467 vascular lesions. The specificity found for DBE is greater than that of VCE (92% vs 82%) possibly because the examiner is able to examine in more detail the alterations found when performing DBE. In contrast, the sensitivity of the VCE is greater than that of the DBE (93% vs 84%) perhaps due to the natural increase in the capacity of the lens of the capsule and the fact that the insufflation of air in the small intestine during the examination with DBE greatly increases the pressure in the organ above the capillary pressure, which prevents the lesions from being observed in this exam. The increase in the diagnostic yield to the vascular lesion is greater when the DBE is performed after VCE.
Through direct meta-analysis of the largest sample ever collected, we compared in isolation the diagnostic methods studied. The diagnostic accuracy of detecting small bowel bleeding from a vascular source is greater with VCE despite reduced specificity. This study sought to remove the bias from the lack of methodological rigor applied in the restrict inclusion criteria with the use of more than two authors for study selection and rigorous protocols accepted worldwide for the choice these studies, thus obtaining more purified results. This study also proposes that in addition to contributing to a greater specificity intrinsic to the examination, performing DBE after the use of VCE contributes to increased accuracy.
The comparison between these two methods through meta-analyses always could be influenced by the technical differences applied in each study. A pertinent study design would include multicentric study with standardized protocols of care, including initial care, standard interval time between onset of symptoms and the first exam, standardized time between the exams, and standardized patient follow-up and bowel preparation.